Resources and support See the Healthy Male site for more information about erectile dysfunction and its treatment. It can be related to declining levels of testosterone in the body. Some people buy sildenafil online without a prescription. Eat a balanced diet that contains heart-healthy foods such as beans, peas, lentils, olive oil, fish and nuts like walnuts and brazil nuts. If you will be taking this medicine for pulmonary arterial hypertension, your doctor will want to check your progress at regular visits.If you have these symptoms, stop taking VIAGRA and contact a doctor right away. have or have had heart problems such as a heart attack, irregular heartbeat, angina, chest pain, narrowing of the aortic valve, or heart failure. have had heart surgery within the last 6 months. have pulmonary hypertension. have had a stroke.  · You’ll likely start with a Viagra dose of 50 mg. You’ll typically take Viagra about 1 hour before sex. You can take the drug 30 minutes to 4 hours before you anticipate sexual activity. Sildenafil (Viagra) is a medicine used to treat erectile dysfunction (ED, also called impotence). Sildenafil works by helping to relax the blood vessels in the penis, allowing more blood to flow in and cause an erection. You should take sildenafil about an hour before planned sexual activity, so it has time to work.